Provided is a pharmaceutical preparation that is suitable for more effectively exhibiting the efficacy of a glutamic acid derivative, which is a GGT-recognizable prodrug, by producing a composition including a glutamic acid derivative capable of rapidly releasing a physiologically active substance by being recognized by GGT, or a pharmacologically acceptable salt thereof； and a block copolymer in which a polyethylene glycol segment is linked to a polyamino acid segment with a hydrophobic group. Particularly, the composition based on a glutamic acid derivative that uses an antitumor compound as a physiologically active substance is capable of effectively accumulating the glutamic acid derivative at a tumor affected area, exhibits a superior effect against tumors, and is capable of suppressing the release of a physiologically active substance in bone marrow tissue where the expression ratio of GGT is low. Therefore, side effects such as myelosuppression, which pose a problem in the use of antitumor drugs, may be avoided.
